JPH113397A - Symbol information reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately decode a bar code even when the position of a bar end part is different from a normal position by determining a scanning line crossing parts corresponding to symbol bars to be a two-dimensional(2D) image from luminance value information and detecting the height and position of the part corresponding to the bar. SOLUTION: When a baggage 7 is carried to a previously set position in a bar code information reder 1, reflected light from a bar code 8 stuck to the baggage 7 forms an image on a 2D CCD 3 having a photoelectric conversion face by an image pickup lens 2. Luminance value information, i.e. bar code information, photoelectrically converted by the CCD 3 is inputted to a frame memory 4 as an 8-bit image signal. An information processor 5 successively reads out the luminance value information crossing all parts corresponding to bars serially from pixels corresponding to the position of a straight line in a frame memory 4 storing the bar code information and sets up a scanning line. Then, the height and positions of bars are discriminated and decoded and the processed information is transferred to a host computer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a symbol information reading apparatus having a two-dimensional image pickup means such as a CCD, and more particularly to a post office or the like for classifying parcels and documents, or improving the efficiency of information input processing. The present invention relates to a symbol information reading device for reading a symbol such as a barcode used.

[0002]

2. Description of the Related Art With the recent remarkable spread of POS (point of sale = point of sale information management system), various symbols represented by barcodes have come to be widely and generally used. Here, the symbol is an appropriate combination of bars and spaces, alphanumeric characters, characters, symbols or those belonging to them, which are printed for optical information recognition, and are used to improve the efficiency of information input. A thing.

A bar code symbol widely used for general consumer goods is JAN (Japanese Article Numbe).
r) codes and EAN (European Article Number) codes. Also, one digit or 2 before the JAN code
There is a distribution barcode to which a digit distribution identification code is added.
These barcode symbols are called one-dimensional barcodes.

[0004] One-dimensional barcodes are simple, accurate, and fast to use when dealing with numerical and character information.
Since it is more advantageous than conventional management methods in terms of cost and the like, it has recently become very widespread.

[0005] A bar code system called a two-dimensional bar code, which can be said to be an extension of the one-dimensional bar code, has been announced. The two-dimensional barcode has an advantage that more information can be handled collectively by stacking one-dimensional barcodes.

On the other hand, around 1960, barcode systems called dot codes, bar nova bar codes, full bar half bar codes, etc. have been successively enacted in Western countries for the mechanization of postal processing and the like, resulting in a reduction in labor costs. The postal service, which has high efficiency, has been promoted in efficiency. In Japan, a new postcode system has been introduced since February 1998, and a new barcode symbol has been adopted.

In general, such a postal bar code tends to increase the amount of information due to the necessity of handling information such as an address. On the other hand, the postal bar code can be printed in a narrow area in order to cope with mails of all sizes and shapes. Is needed.
Therefore, in such a field, the amount of information is increased by defining a plurality of types of bar code bar heights, and improvements such as reducing the bar height as much as possible to narrow the printing range are made. This is usually performed, and a barcode information reading device different from a conventional one-dimensional barcode device is required.

Conventionally, as a bar code information reading device represented by such a postal bar code, for example, as disclosed in US Pat. No. 5,428,211,
For example, there is a type in which a barcode is imaged by two-dimensional imaging means such as a CCD, a barcode image is fetched into a memory, and barcode information is decoded based on the image information.

[0009]

However, the apparatus disclosed in U.S. Pat. No. 5,428,211 can decode full bar half bar codes used in the United States, but decodes bar codes of other countries. Is difficult.

For example, a postal bar code adopted in Japan is a customer bar code as shown in FIG. 10A, and has a bar height ratio of 1: 2: 3. A bar having a height ratio of 2 is divided into an upper bar and a lower bar. A total of four types of bars are defined. And the lower end of each bar of the bar code is not always on the same line.

When the apparatus disclosed in US Pat. No. 5,428,211 attempts to decode such a bar code, it is possible to detect the height of the bar, but in particular to detect the position of a bar having a height ratio of 2. And bar code decoding becomes difficult. Further, it is difficult to define "BAR AXIS" (scanning line connecting the lower ends of the bars) shown in FIG. 9 of the patent publication, and it is also difficult to detect a bar code.

Therefore, the present invention solves the above-described problem, and the lower and upper ends of the bars are not always on the same line, and even if the bars have the same height, the bars having different positions are included in the symbol. It is an object of the present invention to provide a symbol information reading device capable of decoding accurately even in the above case.

[0013]

In order to achieve the above object, the present invention provides an image pickup means for picking up, as a two-dimensional image, a symbol composed of bars and spaces having portions having different light reflectivities; In a symbol information reading device including a storage unit that temporarily stores and holds luminance value information of a two-dimensional image and an information processing unit that decodes information included in the symbol based on the luminance value information, the information processing unit includes: A scan line determination process for determining a scan line that traverses all of the portion corresponding to the bar of the symbol in the two-dimensional image from the luminance value information of the storage unit; and detecting a height and a position of the portion corresponding to the bar. And a bar determination process.

According to this configuration, even if the lower end and the upper end of the bar are not always on the same line, and even if a bar whose height is the same and whose position is different is present in the symbol, it is correctly decoded. can do.

In the scan line determination processing, a plurality of portions corresponding to bars are detected by calculating a luminance value on the scan line, and the portion from the bar detected first to the bar detected last is detected. The position of the midpoint on the scan line is detected. This desirably allows a scan line across all bars of the symbol to be found quickly.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a mode in which the barcode information reading device of the present embodiment is used.

The bar code information reader 1 includes a light source (not shown), an imaging lens 2, a two-dimensional CCD 3, a frame memory 4, and an information processing means 5. The information processing means 5 is connected to a host computer 6. The host computer 6 includes, for example, a CPU and a memory, and can perform various operations such as automatically operating peripheral devices based on information decoded by the barcode information reading device 1. The host computer 6 may be any computer, such as a personal computer, as long as it can support the communication method of the information processing means 5.

Next, the configuration of the barcode information reader 1 will be described in detail. Light source not shown is bar code 8
The diverging light is applied to the luggage 7 to which is attached. The imaging lens 2 forms an image of light reflected from the customer bar code 8 on a photoelectric conversion surface (light receiving area) of the two-dimensional CCD 3 described later. The two-dimensional CCD 3 has a photoelectric conversion surface, and has a function of converting captured image information into luminance value information. The frame memory 4 has a function of temporarily storing and holding luminance value information of a two-dimensional image obtained from the two-dimensional CCD 3. The information processing means 5 includes a CPU, a memory, and the like, and performs various processes, such as estimating the position of a barcode, determining the type of bar, and then performing decoding. The memory includes various registers for storing various constants and variables described below.

In FIG. 1, a bar code information reading device 1
Is conveyed to a preset position. The barcode 8 affixed to the package 7 is, for example, a customer barcode established by the new postal code system in Japan. The reflected light from the bar code 8 is reflected by the imaging lens 2
An image is formed on a two-dimensional CCD 3 having a photoelectric conversion surface. 2
The luminance value information photoelectrically converted by the dimensional CCD 3, that is, barcode information, is taken into the frame memory 4 as an 8-bit image signal. The information processing means 5 performs various processes described below on the barcode information stored and held in the frame memory 4, and transfers the processed information to the host computer 6.

FIG. 2 is a flowchart showing an outline of a barcode decoding algorithm performed by the information processing means 5. First, various parameters such as the frame memory 4, threshold values, and various global variables are initialized (step S1).

Next, an image capturing routine (see FIG. 3)
To load the image into the frame memory 4 (step S2). Next, a barcode detection routine (see FIG. 5) is called to perform a scanning process in the frame memory 4, and a barcode 8 defined in advance is detected in the frame memory 4 (step S3).

As a result of the bar code detection routine in step S3, it is determined whether or not an image corresponding to the bar code exists in the frame memory 4 (step S4). ,
The barcode reading process ends.

If there is an image corresponding to the bar code, a specific bar is designated for the coordinates of each bar obtained from the bar code detection routine, the bar determination routine is called, and the type of bar (high) is determined. (Pod position) is determined (step S5).

This determination routine is performed for all the bars of the bar code (step S6), and if all the bar types have been determined, decoding is performed (step S7). Thereafter, the check digit is confirmed (step S8), and if there is an abnormality in the check digit, the reading process is terminated.

If there is no abnormality in the check digit, the result of decoding is output (step S9), and the barcode reading process is terminated. Next, the various processing routines described above will be described in more detail.

First, the barcode detection routine (step S3 in FIG. 2) will be described with reference to FIGS. FIG.
5A and 5B are diagrams showing the form of a scan line in the frame memory 4, and FIG. 5 is a flowchart showing a barcode detection routine. Hereinafter, the term “scan” is used, which means that when a certain specific straight line is designated, the luminance value information is sequentially read in a line from the pixel corresponding to the position of the straight line in the frame memory 4. This means that the luminance value information is stored in an appropriate array variable and is calculated. Also "scan line"
Means a straight line for scanning in the frame memory 4.

First, the angle of the scan line and the position of the scan line are set (steps S31 and S32). The scan line angle θ0 (hereinafter, referred to as a scan angle) is the angle between the horizontal direction of the frame memory 4 and the direction in which the scan processing is performed. The scan line position c0 (hereinafter, referred to as a scan position) is a point through which the scan line passes.

The scan angle θ0 is initially set to θ0 = 0 degrees (parallel to the horizontal direction), and the scan position c0 is set to a position that divides the area of the imaging area of the frame memory 4 into two equal parts. Scan processing is performed using the scan lines set as described above (step S33). Although details of the scanning process will be described later, the pattern formed by the luminance values obtained in a row and the pattern formed by the bar and space of the barcode defined in advance are compared, and if the patterns match, the patterns match. Processing for detecting the number of bars Bar1 in the region is performed.

Then, it is determined whether or not the detected bar number Bar1 is 67 (the number of bars of the customer bar code is 67). If Bar1 = 67, the scan line is 6
Return to upper routine as it crosses all seven bars.

If Bar1 = 67, then it is determined whether Bar1 ≧ 3. If three or more bars are detected, a detailed detection routine is called (step S34),
While changing the scan angle and the scan position in more detail, it is attempted to detect all, ie, 67 bars.

If Bar1 is less than three, or if Bar1 is not 67 as a result of the detailed detection routine, it is checked whether or not all the scan positions and all scan angles have been detected in the frame memory 4 (step S35, Step S36) If there is a scan position or scan angle that has not yet been detected, the scan position or scan angle is reset, and the above-described routine is repeated.

For example, regarding the scan position, the center position of the frame memory 4 (scan line 1 in FIG. 4A)
To the peripheral position (scan line 2 or scan line 3 in FIG. 4 (a)) or to further narrow the scan line interval (scan lines 4 to 7 in FIG. 4 (a)). By doing so, a scan line that satisfies Bar1 = 67 is found.

As for the scan angle, for example,
As shown in FIG. 4B, +45 degrees (scan line 1-2), 90 degrees, -45 degrees (scan line 1-
3) Re-set as etc.

The method for setting the reset values of the scan position and the angle may be any method. For example, at the scan position, the resetting order is 1, 2, 3, 4, 5, 6, 7 in the scan line shown in FIG.
Or 1,4,5,3,2,6,7. Further, the scan angle may be changed by +45 degrees or may be changed by +30 degrees.

The scan position and the scan angle can be set so that the ratio of the area of the area of the frame memory 4 divided by the scan line is 1 to 10.
This is desirable because the number of scan processes required to detect a barcode does not particularly increase and detection can be performed at a sufficiently high speed. In particular, it is desirable to set the area ratio of the divided regions to be one.

Next, a scan processing routine (step S
33) will be described with reference to FIGS. FIG. 6 is a flowchart of a scan processing routine. FIG. 10A shows a customer bar code, and FIG.
FIG. 10C shows the manner in which the bar code is scanned in the frame memory 4, and FIG. 10C is a partially enlarged view of FIG. 10B.

First, steps S31 and S31 of the upper routine
Each parameter is set based on c0 and θ0 set in 32. Here Bar1 (the maximum bar count)
= 2, Bar2 (bar count value) = 2, T1 (tolerable range)
= 0.6 is set (step S331).

Next, the frame memory 4 is scanned with a scan line passing through the point c0 and having a gradient θ0, and luminance values on the scan line are sequentially obtained (step S332). Then, all the obtained luminance values are differentiated, and the point where the absolute value of the difference value exceeds a certain threshold value and the sign (+ or-) of the difference value are first detected, so that first, Find the boundary point (first edge) that transitions from space to bar. After finding the first edge, the point corresponding to the bar is detected by detecting only the point where the absolute value of the difference value exceeds a certain threshold value, that is, the boundary point (edge) transitioning from the bar to the space and from the space to the bar. Find out.
Then, two edges (for example, a first edge and a next second edge, 3
The midpoint of the bar in the width direction is detected by calculating the midpoint of the fourth edge and the fourth edge (step S33).
3).

Next, the midpoint interval D (i) of successive bars
(I = 1, 2,...) (Step S334),
Further, it is determined whether or not the ratio D (i) / D (i + 1) of the midpoint intervals of the continuous bars is in the range of 0.6 to 1 / 0.6 (step S335). If there is, it is considered that bars at equal intervals are arranged, and Bar2 is incremented by one and counted (step S336). Here, three bars are arranged at equal intervals, and Bar2 is counted as three.
In the bar code system used under the new postal code system in Japan and the bar code system used for postal mail in the United States, there is always a pattern of bars arranged at equal intervals,
What is necessary is just to detect whether or not the intervals between successive bars are substantially equal as in step S335. Also, bar intervals may differ in other barcode systems,
This is dealt with by appropriately changing the conditional expression in step S335 according to the standard of the barcode system.

If Bar2 is greater than Bar1, its Ba
The count value of r2 is recorded as the maximum value of the number of bars as the value of Bar1, and the coordinates of the middle point of the scan line from the first bar to the last bar counted by Bar2 are recorded as c1 (step S337). . Here, B
Since ar2 (= 3) is larger than Bar1 (= 2), Bar1 is recorded as 3, and the area where Bar2 is 3 is from the left edge of the second bar from the left to the right edge of the second bar from the right. Since the middle point of the scan line in this area is the center coordinate of the middle bar, the center coordinate is recorded as the middle point c1.

Then, it is checked whether or not there are bars arranged at equal intervals on all of the scan lines (step S3).
38) When all of the bars on the scan line have been examined, the number of detected bars Bar1 and the center coordinates c1 are transferred to the upper routine (step S339).

Next, a detail detection routine (step S34)
Will be described with reference to FIG. FIG. 7 is a flowchart of the detail detection routine. In the detailed detection routine, the number of detected bars Bar1
Is 3 or more (but not 67).

First, parameters and initial values are set (step S341). The scan position c1 and the scan angle θ1 set in the upper routine are received. . Further, the values of Δc and Δθ, which are displacement amounts of the scan position and the scan angle, are determined. The values of Δc and Δθ are constants Con1 (= 1), Con2 (= 3), Δx (=
0), Δy (= 0) and Bar1 (= 3) (numerical values in parentheses are examples of initial values), Δc = (Δx × Con2, Δy × Con2) Δθ = Arctan (1 / (Bar1 × 2−2) 1)) × Con1.

Con1 is a value of 1 or 0, and indicates whether to change the scan angle. Con2 indicates the amount of translation of the scan line. The larger the value, the greater the amount of translation. x indicates the horizontal direction of the frame memory, y indicates the vertical direction of the frame memory, and Δx and Δy indicate the displacement of the scan position c1 in each direction.

Note that these parameters correspond to Bar1 obtained in a scan processing routine (step S343) described later.
As needed. In addition, the number of scan processes n and the limit value nmax of the number of scan processes are determined.

When Δc and Δθ are determined in step S341, the scan position c and the scan angle θ are set (step S342), and the scanning process is performed again to detect how many bars are present (step S343). This scan process (step S343) has the same processing content as the above-described scan process (step S33) except that the number of scan processes is counted, and thus the description thereof is omitted here.

It is determined whether the number of bars Bar1 detected by this scanning process is larger or smaller than Barmax. If the bar number is larger than Barmax, the values of the scan position c and the scan angle θ are updated to the values of c1 and θ1, respectively. Then, the value of Bar1 is updated to the value of Barmax (step S344). Then, the displacement amount Δc and the displacement angle Δθ of the scan line are reset (step S345). For example, the values of Con1 and Con2 are changed, and the signs are inverted. Alternatively, the values of Δx, Δy, and Con1 may be exchanged, and only the scan angle, only the x direction of the scan position, and only the y direction of the scan position may be sequentially changed and set to perform the scan process.

For example, when the value of Bar1 becomes 50 and approaches the target value of 67, the absolute value of Con2 is reduced, and the movement of the scan position is made smaller. That is, the movement amount Δc of the scan position c1 is equal to Bar
Defined by a decreasing function of 1.

Then, the number n of scan processes is confirmed (step S346). If it is equal to or smaller than nmax, the scan process is performed again. If it is larger than nmax, the detailed detection routine ends and the routine shifts to the upper routine.

In this detailed detection routine, the positions of the upper and lower ends of each bar are irregular, such as a customer bar code, and finally the bar pattern crosses the center position of the bar code where the most found bar code is found. Scan lines are detected convergently.

The process of detecting a barcode by the above-described detailed detection routine will be described with reference to FIG.
If there is no barcode, the scanning process is repeated as shown in FIG.
When a specified number of bars (Bar1 ≧ 3) are crossed, as in 1, the detailed detection routine is called (see FIG. 5).

First, the scan angle is changed as in scan line 1-2. However, scan line 1-2
Since the number of detected bars does not increase, the sign of Δθ is inverted, and the bar has an inclination in the opposite direction to the scan line 1-2 like the scan line 1-3. As a result, the number of detected bars increases, so that the scan position c1 and scan angle θ1 of the scan line are recorded. Then, although Δθ is reset, the value of Con1 does not change, and the absolute value of Δθ is a decreasing function of Bar1, so that Δθ is set to a smaller value and the scanning process is performed again. Every time the number of detected bars Bar1 increases, the scan angle displacement amount Δθ approaches 0 degrees, and the scan angle θ1 converges to an optimal value, that is, a center position across all the bars of the bar code. Also, the scan position is updated as needed to the center coordinates of the area where the bar is found, so that it converges to the optimal point.

Therefore, each time the scanning process is repeatedly performed, the scanning position and the scanning angle converge to the position where all the bars of the bar code exist. FIG.
(B) shows a state in which the detection of all the bars of the barcode is completed by performing the scanning process a total of four times. However, even if one scan line crosses a part of the barcode, the barcode is displayed. Can be detected. Therefore, the number of scans can be remarkably reduced as compared with a method of scanning the entire area of the frame memory 4 and detecting the above-described position of the barcode from the positional relationship of the entire pattern.

Further, Δc and Δθ may be set so that their absolute values become a decreasing function of Bar1, and may be changed to simpler functions to simplify the arithmetic processing such as angles. Here, the decreasing function does not necessarily need to be a function that continuously decreases, and may be a function in which the value of the function decreases stepwise as Bar1 increases.

When the number of scans n exceeds nmax and a plurality of scan positions c1 are found on a scan line in the scan processing, n is initialized to 1 and the scan position is moved to another position. May be performed. In particular, when there are many noises such as characters and dirt around the barcode, the scanning position detected at the first time is not always correct, so that such processing significantly improves the reading reliability. improves.

Next, a bar code bar discrimination routine (step S5) will be described with reference to FIGS.
FIG. 8 is a flowchart of a bar determination routine, and FIG. 9 is a diagram showing how a height of a certain bar is detected.

Before proceeding to this determination routine, all the bars of the customer barcode have already been detected, and the center coordinates of each bar have been recognized by the barcode detection routine (step S3).

In the determination routine (step S5), first, as shown in FIG. 9A, P (1) is set for one of the center coordinates of the detected bar, and the P (1) is set.
P (2) and P (3) are further set at the same position as (1) (step S51).

Next, a point adjacent to the point P (2) and having the greatest distance from P (3) is defined as P
As (4) (step S52), P (2) and P (4)
Then, a difference between the luminance values is calculated (step S53). Then, it is determined whether or not the absolute value of the difference is equal to or smaller than a predetermined threshold (step S54). That is, in step S54, it is determined whether P (4) is located on the bar or is located off the bar and on the space. It is assumed that P (4) is located on the space unless it is below the threshold value.

If the absolute value of the difference value is equal to or smaller than the threshold value, the coordinates of P (4) are updated as the coordinates of P (2), and steps 52 to 54 are repeated. If the absolute value of the difference value is not smaller than or equal to the threshold value, another point adjacent to P (2) is checked (step S55), and if there are still points adjacent to P (2), One point is reset as P (4) (step S52), and steps S53 to S54 are repeated.

P (2) is adjacent to P (2) and P (2)
For all the points far from (3), if the absolute value of the difference between the luminance value and P (2) is not equal to or smaller than the threshold value, that is, as shown in FIG. ) Is located at the end (corner) of the bar, since P (4) cannot be set, the coordinates of P (2) are recorded and P (4) is recorded.
The process related to (2) ends.

Next, the same processing is performed for P (3). As a result, as shown in FIG.
(3) is located on the diagonal of P (2). Then, a line segment connecting the two points is obtained from the coordinates of P (2) and P (3), and the height of the bar is obtained from the length of the line segment.

As described above, there are three types of bar heights of the customer barcode (height ratio 1: 2: 3), and the bar height of each bar is compared with the bar at the left end or right end (height ratio 3). The height can be determined. The bar with a height ratio of 2
Although two types are defined by the position in the height direction in the barcode, this position is determined by determining whether the midpoint of the line connecting P (2) and P (3) is located above the scan line or below. It is determined by whether it is located on the side. For example, in the case of the bar shown in FIG. 9D, since the middle point of the line connecting P (2) and P (3) is above the scan line, this bar is arranged above the barcode. It is determined that the bar has a height ratio of 2. The position of the bar is determined by P
The determination may be made based on whether the midpoint of the line connecting (2) and P (3) is located above or below P (1).

In this determination routine, an arbitrary bar can be compared with the left and right long bars, and the type of the bar can be determined only based on the relative relationship between the height and the position. It is placed at an angle to the reader, and the captured image is distorted,
Identifies the type of bar even under bad conditions, such as when the barcode printing accuracy is poor and printing runs off slightly, or when the long side of the bar is not perpendicular to the short side of the bar can do.

In this discrimination routine, the number of moving points (P (2) and P (3)) does not need to be two. Detects one corner and not only the bar height,
Since the width can be calculated, it is possible to cope with various bar code symbol systems.

As described above, by performing the bar determination routine for all the bars, the types of all the bars are determined. In each of the above routines, any bar code symbol having a pattern in which the bars are arranged at predetermined intervals may be used. Therefore, the bar code symbol is not limited to the Japanese postal bar code described in the above embodiment, and may be a U.S. Even for a postal bar code, a 4-state bar code in the UK, a bar bar bar code in Germany, etc., the number of bars is set in advance, and the setting of the bar interval is changed as appropriate. If the number is counted, it can be easily handled.

Since symbols are detected based on the total number of bars, the size of a printed barcode changes, or the size of a barcode symbol imaged according to the distance from the image pickup means changes. Even if it occurs, it can be dealt with without any problem.

The present invention can be summarized as follows. (1) imaging means for imaging a symbol composed of bars and spaces having different light reflectance portions as a two-dimensional image, storage means for temporarily storing and holding luminance value information of the two-dimensional image, A symbol information reading device having information processing means for decoding information contained in the symbol based on luminance value information, wherein the information processing means comprises: 1) the luminance value information stored in the storage means; Symbol information characterized by performing scan line determination processing for determining a scan line that traverses all of the portion corresponding to the bar, and 2) bar determination processing for detecting the height and position of the portion corresponding to the bar. Reader.

According to this configuration, even if the lower end and the upper end of the bar are not always on the same line, and even if the bar has the same height but the position is different within the symbol, the decoding is performed correctly. can do. (2) In the symbol information reading device according to (1), in the scan line determination processing, a plurality of portions corresponding to bars are detected by calculating a luminance value on the scan lines, and a bar detected first is provided. A symbol information reading device for detecting a position of a middle point on the scan line from the first to the last detected bar.

According to this configuration, a scan line crossing all the bars of a symbol can be found quickly. (3) In the symbol information reading device according to the item (2), the setting of the position of the scan line in the scan line determination processing is performed on the scan line from the first detected bar to the last detected bar. Assuming that the position of the middle point is c1, the number of portions corresponding to bars on the scan line passing through the position c1 is Bar1, and the position of the next set scan line is c, the displacement amount from the position c1 to the position c A symbol information reading device wherein Δc is a decreasing function of Bar1.

According to this configuration, a scan line crossing all the bars of the symbol can be found earlier. (4) In the symbol information reading device according to (2), the setting of the angle of the scan line in the scan line determination processing is performed on the scan line from the first detected bar to the last detected bar. The angle of the scan line passing through the position of the midpoint is θ1, and the number of parts corresponding to the bar on the scan line at the angle θ1 is B.
ar1, the angle of the scan line to be set next is θ, the displacement angle amount Δθ from the angle θ1 to the angle θ is Bar1
A symbol information reading device characterized by a decreasing function of

According to this configuration, a scan line crossing all the bars of a symbol can be found earlier. (5) In the symbol information reading device according to the item (1), in the bar discrimination processing, arbitrary two points P (2) and P (3) are set in a portion corresponding to the bar, and the two points P (2) and P (3) are set.
(2) and P (3) are located farthest apart from each other, and the change in the luminance value before and after the movement is equal to or less than the threshold value.
The points P (2) and P (3) are moved, respectively,
(2) The length of a line segment connecting the point P (3) is detected, and the height of a portion corresponding to the bar is detected by detecting the ratio of the length to another bar. Symbol information reading device.

According to this configuration, the height of the bar can be detected. (6) In the symbol information reading device according to the item (5), the bar discrimination processing includes the point P (2) and the point P (3).
Detecting the middle point from the length of the line segment connected to the bar, and detecting the position of the portion corresponding to the bar by detecting which side the middle point is located across the scan line. Symbol information reading device.

According to this configuration, the position of the bar in the symbol in the height direction can be detected.

[0075]

As described above, according to the present invention,
Even if the lower end and the upper end of the bar are not always on the same line, and even if the bar has the same height but the position is different in the bar code, it can be correctly decoded.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a barcode information reading device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an outline of a barcode decoding algorithm performed by the information processing means 5;

FIG. 3 is a flowchart showing an image capturing routine.

FIGS. 4A and 4B are diagrams showing each aspect of a scan line in a frame memory 4. FIGS.

FIG. 5 is a flowchart showing a barcode detection routine.

FIG. 6 is a flowchart of a scan processing routine.

FIG. 7 is a flowchart of a detail detection routine.

FIG. 8 is a flowchart of a bar determination routine.

FIG. 9 is a diagram showing how a height of a certain bar is detected.

10 (a) shows a customer barcode, FIG. 10 (b) shows how the barcode is scanned in the frame memory 4, and FIG. 10 (c) shows FIG.
It is the elements on larger scale of 0 (b).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Barcode information reading device 2 Image pickup lens 3 Two-dimensional CCD 4 Frame memory 5 Information processing means 6 Host computer 7 Package 8 Customer barcode

Claims (2)

[Claims] An image pickup means for picking up, as a two-dimensional image, a symbol composed of bars and spaces having portions having different light reflectances, and a storage means for temporarily storing and holding luminance value information of the two-dimensional image. A symbol information reading device having information processing means for decoding information of the symbol based on the brightness value information, wherein the information processing means determines the symbol of the symbol in the two-dimensional image from the brightness value information of the storage means. A symbol information reading apparatus comprising: a scan line determining process for determining a scan line that traverses all of a portion corresponding to a bar; and a bar determining process for detecting a height and a position of the portion corresponding to the bar. . 2. The symbol information reading device according to claim 1, wherein the scan line determination processing detects a plurality of portions corresponding to bars by calculating a luminance value on the scan line, and is detected first. A symbol information reading device for detecting a position of a midpoint on the scan line from a bar to a bar detected last.